BACnet Offers Path to Energy Efficiency

Whether it’s because of volatile energy prices or concerns about an organization’s carbon footprint, top management has become aware that commercial buildings gobble up vast amounts of energy. The statistics are telling. Commercial buildings account for roughly 35 percent of the nation’s electricity use, according to the U.S. Department of Energy. HVAC and lighting systems make up a large portion of that energy use.

With such data in mind, many facility executives have set out to make better energy management decisions. Visibility of energy use information is a crucial part of the equation to empower end users for behavior change, says Tom Zaban, vice president of sales and marketing of Reliable Controls.

“It’s helpful for occupants to see their consumption of electricity over time, for example,” Zaban says. “They can see the consequences of turning lights off vs. leaving them on. Information empowers users and prompts them to change their environment.”

Automation helps to bring such information to the minds of the facilities team, tenants and other occupants.

“Like any digital control system, BACnet systems automate much of the activity related to a facility’s energy usage,” says Ben Dorsey, vice president of marketing and communications for KMC Controls. “This includes such common functions as scheduling, trend logs and reports. Beyond the capabilities of a typical control system, however, a BACnet system allows multiple vendor systems to communicate ‘mission critical’ data to one another.”

This interoperability of the building automation system and subsystems through the open BACnet protocol offers a highly effective solution for energy management strategies in three important ways:

It allows facility executives to define the level of system efficiency and ease-of-use that is most beneficial.

It provides freedom to purchase and easily integrate an automation system and individual components that combine to meet the system requirements, regardless of manufacturer.

It doesn’t tie facility executives to the original automation system manufacturer or require them to purchase costly upgrades to one-of-a-kind software gateways when they expand or upgrade their systems in the future.

“Interoperability adds a whole new dimension to real-time control and feedback and allows facility personnel to fine tune energy management strategies based on subsystem and external inputs, such as weather data and forecasts and utility rate information,” says Roy Kolasa, open system integration market manager for Honeywell global offer management. “Monitoring energy systems and trending data is one method to identify operational issues and establish energy management benchmarks.”

Put another way, more information makes it easier to take action.

“The combination of these services between applications provides buildings with the ability to dynamically modify their load profiles, optimizing energy consumption based on current demands of the building’s occupants,” says Brian Dutt, vice president of sales and marketing for Delta Controls.

Because BACnet is an open, standard protocol, data from different systems is available in one common format, independent of vendor. This is one of the most notable reasons for using BACnet-compatible systems in energy management activities, says Mike Olson, manager of HVAC applications for ABB.

“In the old days, if you had one company’s system in your building, you needed to have that same company’s front-end software on your computer to make any changes remotely,” he says. “But, if you operate with BACnet, you can access an entire building’s energy and systems usage patterns through a Web browser on any computer. “

BACnet equates to simpler integration, says Mark Clark, region manager for Automated Logic Corp. “Being able to take a BACnet-based system and have it easily communicate with other BACnet-based building systems makes it easier to access, transfer and manage operating information,” Clark says. “The more information available, the more effective energy management strategies can be put into place.”

One thing to be aware of: Because BACnet itself is simply a protocol, installing a BACnet-based system doesn’t mean it will immediately produce better energy savings than another system.

“Nothing inherent in BACnet promises this,” says Chris Hollinger, senior product manager at Siemens. “You have to take the next step and discover what creates better savings and how BACnet helps.”

Understanding Energy Use

Interoperability is the primary way BACnet helps generate better energy savings. With open, interoperable systems, views of the entire building and its systems are easier to create in the energy management system and can be accessed from any computer.

“One of the most important factors in energy management is the ability to see and understand how a system is performing and where energy is used,” says Steven Bushby, leader of the mechanical systems and controls group at the Building and Fire Research Laboratory for the National Institute of Standards and Technology. “Interoperability creates an environment where building operators and managers can see all of their systems from one interface and take appropriate actions to make maintenance and control adjustments that have important energy implications.”

KMC Controls, for example, is involved in a significant project where executives at a client company desire better energy management across hundreds of geographically dispersed retail facilities. “Our BACnet device controls lighting and one other confidential system and feeds data to another vendor’s BACnet-enabled device, which provides the Web-based reporting to the appropriate executives,” Dorsey says. “Thus, in this case, we can see several brands of equipment in at least three distinct building systems, all co-existing nicely for the sole purpose of managing the company’s energy usage.”

BACnet allows automatic control of equipment in the building through open, standard protocols, no matter the manufacturer, and delivers much more detailed, composite energy usage information than if the systems operated independently from one another. According to Dutt, the main issue at most facilities is that the available information regarding energy consumption is typically not granular enough to calculate and measure return on investment (ROI) on individual energy management initiatives.

“Most facilities have primary utility information but do not have adequate sub-metering installations for trending of energy consumption,” he says. “With a BACnet-based system, it is relatively easy to integrate with sub-meter devices and integrate them into a BACnet automation system for trending and analysis. The information can then be monitored, trended, analyzed and used to both adjust energy management strategies, as well as clearly identify a project’s ROI.”

According to Larry Haakenstad, director of sales, Alerton, BACnet provides more useful information from equipment than older, proprietary systems did. “For instance, a variable frequency drive (VFD) used to be a single control point for most building management systems. Now, with a BACnet interface, the VFD may make available 25 or more pieces of information,” Haakenstad says.

The result? Designers can put together more sophisticated control sequences for that unit or multiple units. Additionally, pertinent system information now can be recorded and tracked for energy-management analysis.

Consider an office building in Minnesota, a state where spring can be warm or cold, depending on the day. A typical stand-alone system will control the boiler and circulating pumps based upon the outside air temperature, using energy to generate hot water in case it is needed.

“The fully BACnet-integrated system will allow the room temperature controls to communicate with the boiler to reduce the hot water temperature in order to optimize, if not shut off and eliminate, unnecessary heating plant operation if the indoor temperature is fine and the occupants are satisfied,” Clark says. “Why provide full heating or cooling if the occupants are already comfortable?”

Reaping the most reward from the energy management components of a BACnet system comes down to careful planning, Bushby says.

“Evaluating existing or future building stock, understanding the life cycle impacts of building automation on planning, design, construction, operations, obsolescence and plan implementation will help ensure success,” he says. “Implementing a BACnet solution will facilitate interoperability and improve life cycle operations of the automation system but only with advanced planning and good management.”

“When you install an open energy management system, you install a long-term asset,” says Andy McMillan, president and CEO of Teletrol Systems Inc. “You maximize value and better manage the new realities of the energy marketplace.”

Choose Carefully

Facility executives should understand that moving into the world of multivendor interoperable BACnet systems creates new demands on procurement specifications, project management and commissioning. Equipment and subsystems need to be thoughtfully designed with the monitoring and control functionality necessary to execute energy management strategies.

“When putting together a multivendor BACnet system, don’t fall into the trap of just selecting the lowest cost products for each application — it may end up costing more overall,” says Jon Williamson, product manager for TAC. “You must consider the BACnet capabilities of each device. Can it alarm, trend and schedule on its own? Or will the device rely on other BACnet devices to do the job for it?”

One component of the process includes having the proper point data available to the building automation system and other BACnet clients.

“In unofficial surveys I have done, I was amazed to repeatedly find that less than 50 percent of the new building automation and energy management systems today are tied into the main electric meter for a building or some other form of sub-metering,” Clark says. “A simple two-wire connection to a utility meter pulse output is one of the most cost-effective points to bring into the BAS.”

Specifying devices and equipment that are listed by the BACnet Testing Laboratories (BTL) and support alarming, trending, scheduling and priority array also helps maximize the protocol’s energy management benefits.

“There is so much facility executives can do with BACnet,” Olson says. “It provides a concrete measurement tool, and if you can measure it, if you can show trends and flag them, you can change habits. Real-time information simply means better energy management decisions.”

This information can jumpstart a complete revamping of energy use habits in a facility.

“It turns into an energy efficiency audit almost by default,” McMillan says. “The areas of waste are clearly outlined in the information the system provides, and you wind up lowering your overall use because you can see where the waste is. You can see what the true requirement for energy use is and compare it to the way it has always been done. It almost always leads to more efficient normal operation.”